Nu, nu-difluoramides and method for preparing same



United States Patent 3,388,160 N,N-D1FLUORAMIDES AND METHUD FGR PREPARING SAME Jeremiah P. Freeman and Robert C. Pehy, Huntsville,

Ala., assiguors to Rohm & Haas Company, Philadelphia, Pa., a corporation of Delaware No Drawing. Filed Feb. 8, 1961, Ser. No. 87,968

10 Claims. (Cl. 260558) This invention concerns amides containing the NF group and processes for the preparation thereof.

The compounds of the present invention are of the general formula RCONF in which R is hydrogen, alkyl, aryl, or alkaryl.

The compounds of the present invention are of value as a source of difiuoroamine, HNF Thus, aqueous or alcoholic acid hydrolysis of the N,N-difluoramides of the present invention produces HNF HNF by addition to ketones, produces alcohols containing NF groups which alcohols, when esterified with unsaturated acids, give polymerizable monomers. The polymers of such monomers are of value as solvent resistant coatings, as binders for caulking compounds and, when plasticized, are useful as components of pressure sensitive adhesives.

The compounds of the present invention are prepared by reacting diketones of the formula RCOCOR in which R is as hereinbefore described with tetrafiuorohydrazine, N F while subjecting the reaction mixture to ultraviolet irradiation.

The dihetones suitable for use in the present invention can be prepared by thecatalytic dehydrogenation of acyloins obtained by the reaction of esters and sodium. Thus,

Na -11: 2RC02E2H5 RCHOHCOR RCOCOR The preparation of N F is set forth by Colburn et al. in I.A.C.S. 80, 5004 (1958) and the information therein is incor orated herein by reference. 14 R, is prepared by the thermal reaction of nitrogen trifiuoride with fluorine acceptors, such as copper, bismuth and arsenic.

The diketones suitable for use in the process of the present invention include glyoxal, 2,3-butanedione, 2,3- pentanedione, 3,4-heptanedione, 2,3-oetanedione, l-phenyl-2,3-butanedione, 1-benzyl-2,3-pentanedione, S-p-tolyl- 2,3-pentanedione, 6-naphthyl-3,4-hexanedi0ne, 1,2-diphenylethylanedione (benzil) and methylphenyl diketone.

Any source of UV light can be employed to effect the reaction between N 12, and diketones. Thus, the mixture of reactants in a Pyrex reactor can be exposed to sunlight. More satisfactory, however, is an artificial source of ultraviolet light and lamps having a high output of ultraviolet light are commercially available.

The temperature of reaction will vary depending on the particular diketone employed, since it is preferred to carry out the reaction in the gas phase. The reaction temperature will range from 25 C. to 200 C.

The reaction time will vary depending on the reactivity of the diketone and the intensity of the ultraviolet light. The reaction time will vary from 2 hours to 24 hours.

The molar ratios of diketone to N 1 can be varied widely and still be within the scope of the invention. Theoretically, the reaction requires one mole of N F for each mole of diketone but since any unused N 1 can be readily recovered, the preferred embodiment employs an excess of N 1 in order to obtain higher yields of the desired product. Thus, from 2 to up to 10 moles of N F may be employed per mole of diketone, the excess being recovered and reused. Preferred is the use of 2 to moles of N 1 per mole of diketone.

3,388,180 Patented June 11, 1968 It is preferred to carry out the reaction in an anhydrous inert, i.e. oxygen-free, atmosphere, and so the reaction vessel is flushed with an inert gas such as nitrogen, helium or argon before the reactants are charged to the vessel. The inert anhydrous atmosphere is maintained throughout the reaction.

The following examples set forth certain well-defined embodiments of the application of this invention. They are not, however, to be considered as limitations thereof, since many modifications may be made without departing from the spirit and scope of this invention.

Unless otherwise specified, all parts are parts by weight. All temperatures are eentigrade unless otherwise noted.

EXAMPLE I Two grams of biacetyl and 1030 cc. of N F were irradiated in a Pyrex bulb with Hanovia EH-4 ultraviolet lamp for 16 hours. The product, N,N-difiuoracetamide, condensed at C., was removed, and distilled in vacuo, Bl. 4547/atm. press.

Analysis.Calculated for C H F NO: C, 25.27; H, 3.18; N, 14.74; F, 39.98. Found: C, 26.36; H, 3.11; N, 14.40; F, 37.88.

EXAMPLE II Preparation of N,N-difluorobenzamide A 1 l. three-necked Pyrex flask equipped with magnetic stirrer, manometer, and inlets to N N F and a vacuum pump, was charged with 5 g. (2.4 10- mole) of benzil in 300 cc. of methyl cyclohexane. The system was flushed with N for 5 minutes. More of the N was evacuated with the vacuum pump, and N F was admitted until atmospheric pressure was registered on the manometer. The contents of the flask were stirred magnetically at ambient temperature and irradiated with a Hanovia EH4 lamp for 4 hours. Periodic additions of N F were made to keep the system near atmospheric pressure. At the completion of the reaction the system was flushed thoroughly with nitrogen and the reaction mixture distilled with an efiicient fractionating column. There was obtained 1.8 g. of N,N-ditluorobenzamide, BE. 36 C./1 mm.

A.'zalysis.-Calculated for C I-I ONF C, 53.51; H, 3.19; N, 8.91; F, 24.20. Found: C, 54.28; H, 3.67; N, 8.78; F, 21.54.

Treatment of a sample with H O rapidly produced benzoic acid and HNF EXAMPLE III Preparation of N,N-difluoroformamide A 1 l. Pyrex reaction bulb was charged in vacuo with 0.010 mole N 11 and 0.0043 mole of monomeric glyoxal (prepared by the thermal depolymerization of polyglyoxal in the presence of P 0 The reaction bulb was irradiated at ambient temperature with a Hanovia EH-4 lamp for 35 minutes after which time the yellow color of the monomeric glyoxal had disappeared and the reaction bulb was coated with White solid. The bulb was cooled in liquid nitrogen and the non-condcnsable fraction removed with a Toeppler pump, measured and analyzed by mass spectrometry. The fraction amounted to 0.0081 mole and was found to be pure CO. The remainder of the reaction mixture was fractionated thru traps at -80, and -196 C. The -196 fraction amounted to 0.0081 mole. Mass spectral analysis showed only N 1 containing a trace of N 0. The l20 fraction amounted to 0.00087 mole; mass and infrared spectra showed it to contain 13% HNF with the remainder being N,N-difluoroformamide,HCONF There was no 80 fraction. The solid residue in the reaction bulb was not characterized.

3 The infrared spectrum of HCONF is characterized by the following absorption bands C-H, 3.40 C O, 5.50 1; NP, 9.33, 10.6, and 12.4

The mass spectrum of N,N-difluoroformamide is given below. The sample contained 3% HNF as contaminant.

M/e R I Ion 26 1. 2 CN 27 2. 6 HCN+ 28 8. 2 CO 29 100 HUO 5. 4 NF- 34 8. 2 HNF 42 3. 4 CON 43 4. 7 HCON 47 1.2 COF 48 0. S 1IOOF+ 52 2. NFz 53 1. 1 HN F2 The following reactions were carried out as additional proof of structure.

RCONF in which R is as hereinafter defined which comprises irradiating with ultraviolet light a mixture of tetrafiuorohydrazine, N F and a diketone of the formula RCOCOR in which R is a member of the group consisting of H, a C to C alkyl group, phenyl, benzyl, fi-phenyl ethyl, flp-tolyl ethyl, and fi-naphthyl ethyl, and recovering the N,N-difiuorarnide from the reaction mixture.

2. A process as set forth in claim 1 in which the reaction temperature is from 25 C. to 200 C.

3. A process as set forth in claim 1 in which the molar ratio of diketone to N E; is from 1 to 2 to 1 to 10.

4. A process as set forth in claim 1 in which the molar ratio of diketone to N R; is from 1 to 2 to 1 to 5.

5. A process as set forth in claim 1 in which the reaction is conducted in an anhydrous atmosphere which is inert under the reaction conditions.

6. A process as set forth in claim 5 in which the inert atmosphere is selected from the group consisting of nitrogen, argon and helium.

7. A compound of the formula RCONF in which R is a group selected from the group consisting of hydrogen, a C to C alkyl group, phenyl, benzyl, flphenyl ethyl, fl-p-tolyl ethyl, and ,B-naphthyl ethyl.

8. N,N-difluoracetamide.

9. N,N-difluorobenzamide.

10. N,N-difiuoroformarnide.

References Cited Emeleus et al.: Advances in Inorganic Chemistry, vol. 3 (1961), pp. 356-66.

NICHOLAS S. RIZZO, Primary Examiner.

I. NARCAVAGE, Assistant Examiner. 

1. A PROCESS FOR THE PREPARATION OF N,N-DIFLUORAMIDES OF THE GENERAL FORMULA
 7. A COMPOUND OF THE FORMULA 